The aforementioned Provisional Application No. 60/194,983 is hereby incorporated by reference.
The present invention relates to a disc drive microactuator, and more particularly to a high resolution positioning mechanism implemented at the slider level for selectively moving a transducer portion of the slider radially with respect to circumferential data tracks of a rotatable disc.
The density of concentric data tracks on magnetic discs continues to increase (that is, the size of data tracks and radial spacing between data tracks are decreasing), requiring more precise radial positioning of the head. Conventionally, head positioning is accomplished by operating an actuator arm with a large-scale actuation motor, such as a voice coil motor, to radially position a head on a flexure at the end of the actuator arm. The large-scale motor lacks sufficient resolution to effectively accommodate high track-density discs. Thus, a high resolution head positioning mechanism, or microactuator, is necessary to accommodate the more densely spaced tracks.
One promising approach for high resolution head positioning involves employing a high resolution microactuator in addition to the conventional lower resolution actuator motor, thereby effecting head positioning through dual-stage actuation. Various microactuator designs have been considered to accomplish high resolution head positioning. Some designs are employed to deform disc drive components such as the actuator arm or the flexure in order to achieve minute displacements by bending. Other designs introduce a separate microactuator component at an interface between disc drive components. While many previous microactuator designs are able to deliver satisfactory micropositioning performance, their effectiveness is inherently limited by the sheer mass that the microactuators are designed to move. In order to move or bend one or more of the disc drive components, the microactuator employed must provide a relatively large amount of force, which requires either a complex or relatively massive microactuator motor mechanism.
A microactuator designed to move only a transducer-carrying portion of the slider with respect to the main portion of the slider is disclosed in U.S. application No. 09/007,007 which is assigned to Seagate Technology, Inc., the same assignee as the present invention. The present invention provides another microactuator for moving a transducer-carrying portion of the slider with high resolution and frequency response, in a configuration that is readily and inexpensively manufactured by thin-film processing techniques.
The present invention is a microactuator built at the slider level for achieving high resolution positioning of a transducing head with respect to a track of a rotatable disc having a plurality of concentric tracks in a disc drive system. The slider includes a main body carried by a flexure. A stator portion extends from the main body, and a plurality of beams extend from the stator portion, the beams being flexible in a lateral direction. A rotor portion is connected to the stator portion by the plurality of beams, forming a gap between the stator portion and the rotor portion. The rotor portion carries the transducing head. A plurality of stator electrodes are formed on the stator portion, and a plurality of rotor electrodes are formed on the rotor portion to confront the stator electrodes across the gap. Control circuitry applies selected voltages to the stator electrodes and the rotor electrodes to create a force in the lateral direction for moving the rotor portion with respect to the stator portion of the slider, thereby finely positioning the transducing head.